SWIRLER FOR A BURNER OF A GAS TURBINE ENGINE, BURNER OF A GAS TURBINE ENGINE AND GAS TURBINE ENGINE

Abstract

A swirler for a burner of a gas turbine engine, having a plurality of vanes extending from an outer radius of the swirler to an inner radius of the swirler and a plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel, located essentially at an outer radius of the swirler, to a radially inner end of the mixing channel, located essentially at an inner radius of the swirler, at least one main injector for providing fuel for a main flame of the gas turbine engine, the main injector arranged at and/or in at least one of the mixing channels, and at least one pilot injector for providing fuel for a pilot flame of the gas turbine engine. A burner of a gas turbine engine and a gas turbine engine include the swirler.

Claims

1. A swirler for a burner of a gas turbine engine, the swirler comprising: a central axis, a base plate having a base plate surface, an annular array of vanes mounted on the base plate and each vane having a first side surface and a second side surface which meet at a trailing edge, wherein the first side surfaces, the second side surfaces the base plate surfaces define a plurality of mixing channels between the vanes to channel air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, wherein at least one vane has a height and the trailing edge is at an inner radius from the central axis, at least one main injector for providing fuel for a main flame, the main injector arranged at and/or in at least one of the mixing channels, and at least one pilot injector for providing fuel for a pilot flame, wherein the at least one pilot injector has an outlet that is arranged within 30% of the height from the base plate surface and between 80% and 150% of the inner radius.

2. The swirler according to claim 1, wherein the at least one pilot injector is at least partly housed within or through an orifice in any one or more of the vane or base plate.

3. The swirler according to claim 1, wherein the at least one pilot injector is arranged radially inwardly of the at least one main fuel injector.

4. The swirler according to claim 1, wherein the at least one pilot injector is arranged at a distance from a center of the swirler of 100% to 120%, of the inner radius of the swirler.

5. The swirler according to claim 1, wherein the at least one pilot injector is at least partly arranged in a region between an extended plane of the first side surface and an extended plane of the second side surface.

6. The swirler according to claim 1, wherein the at least one pilot injector is constructed as a fuel injection lance.

7. The swirler according to claim 6, wherein the fuel injection lance comprises an angled tip.

8. The swirler according to claim 1, wherein the at least one pilot injector comprises pilot fuel injectors arranged relative to alternate mixing channels or vanes.

9. The swirler according to claim 8, wherein the at least one main injector comprises main fuel injectors arranged relative to alternate mixing channels.

10. The swirler according to claim 1, wherein the at least one pilot injector is arranged at and/or extends into the at least one mixing channel between 5% to 10% of the height of the trailing edge.

11. The swirler according to claim 1, wherein the swirler comprises at least two pilot injectors, the at least two pilot injectors arranged at or near different mixing channels of the swirler.

12. The swirler according to claim 1, wherein the at least one pilot injector and the at least one main injector are arranged at and/or in different mixing channels of the swirler.

13. The swirler according to claim 1, wherein the at least one pilot injector and the at least one main injector are arranged at different heights and/or extend into different heights of the respective at least one mixing channel of the swirler and/or cause fuel to penetrate to different heights of the respective at least one mixing channel of the swirler.

14. A burner of a gas turbine engine, comprising a swirler and a combustion chamber, wherein the swirler is constructed according to claim 1.

15. A gas turbine engine, comprising at least one burner, wherein the burner is constructed according claim 14.

16. The swirler according to claim 6, wherein the at least one pilot injector is constructed as a removable fuel injection lance.

17. The swirler according to claim 13, wherein the fuel penetrates to different heights of the respective at least one mixing channel of the swirler by regulation of an injection velocity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention is described with respect to the accompanied figures. The figures show schematically:

[0029] FIG. 1 shows a sectional view of a gas turbine in which the present swirler can be incorporated,

[0030] FIG. 2 shows a sectional view of a part of a first embodiment of a swirler according to the invention,

[0031] FIG. 3 shows a side view of a part of a second embodiment of a swirler according to the invention,

[0032] FIG. 4 shows a sectional view of a third embodiment of a swirler according to the invention, and

[0033] FIG. 5 is a section through the swirler, burner, prechamber and part of the main combustion chamber as shown via section A-A in FIG. 4.

DETAILED DESCRIPTION OF INVENTION

[0034] Elements having the same functions and mode of action are provided in FIGS. 1 to 4 with the same reference signs.

[0035] In FIG. 2 a sectional view of a first possible embodiment of a part of a swirler 50 according to the invention is shown. In this partial view, two vanes 54 and a mixing channel 56 in between are depicted. The mixing channel 56 extends from an outer end 58 to an inner end 60, wherein the outer end 58 is essentially located at an outer radius 62 of the swirler 50 and the inner end 60 is essentially located at an inner radius 64 of the swirler 50. Air 24 is channelled through the mixing channel 56 from the outer end 58 to the inner end 60, both for the main flame and the pilot flame of the burner 30 of the gas turbine engine 10 (see FIG. 5). In the mixing channel 56 a main injection means 52 is located to provide fuel for the main flame. It is positioned such that the air 24 flowing past the main injection means 52 is automatically atomizing the fuel and transporting the fuel as an air/fuel mixture into the main flame region.

[0036] In addition a pilot injection means 70 is also positioned in the mixing channel 56. In this embodiment of a swirler 50 according to the invention, the pilot injection means 70 is positioned at a smaller radius in respect to the centre of the swirler 50 than the main injection means 52. The pilot injection means 70 is positioned such that the air 24 flowing past the pilot injection means 70 is automatically atomizing the fuel and transporting the fuel as an air/fuel mixture into the pilot flame region. No further elements are necessary for atomization and/or guiding the fuel/air mixture to the pilot flame region. The accumulation of carbon build up can therefore be prohibited in an especially easy way.

[0037] FIG. 3 shows a side view of a part of a second embodiment of a swirler 50 according to the invention. A single vane 54 and the adjacent mixing channel 56 are shown. An arrow symbolizes the air 24 channelled through the mixing channel 56 from its outer end 58 located essentially at the outer radius 62 of the swirler 50 to its inner end 60 located essentially at the inner radius 64 of the swirler 50. Several possible embodiments of a pilot injection means 70 are depicted. One of the pilot injection means 70 is constructed as a fuel injection lance 76. Such a fuel injection lance 76 can advantageously be constructed as a removable fuel injection lance 76. A replacement of the pilot injection means 70 is in this case possible in a very easy manner, especially if the fuel injection lance 76 can be removed from outside of the assembly of the swirler 50.

[0038] Further, the fuel injection lance 76 shown in this figure comprises an angled tip 74. At the end of the angled tip 74 an injection point 72 of this pilot injection means 70 is positioned. By choosing the angle of the angled tip 74, either in respect to the residual body of the pilot injection means 70 or in respect to the channelled air 24 or in respect to both, an especially effective injection of pilot fuel into the channelled air 24 can be achieved. This angled tip 74 can be for instance as depicted an external bending of a head portion of the at least one pilot injection means 70, but also an internal angled tip 74, for instance comprising an angled conduit inside the tip of the at least one pilot injection means 74, is possible. Especially a penetration of pilot fuel into the main flame can easily be prevented. The other embodiment of the pilot injection means 70 comprises two injection points 72. These injection points are positioned in the vane 54, in particular at the trailing edge 66 of the vane 54. Due to the positioning in the vane 54, no further elements are necessary to construct the pilot injection means 70. Therefore this embodiment is an especial easy way to construct a pilot injection means 70. At the trailing edge 66 of the vane 54, the air 24 from different mixing channels 56 are joining by what turbulences can occur. These turbulences support the atomizing of the fuel provided by the pilot injection means 70. An even better fuel/air mixture can therefore be achieved.

[0039] In FIG. 4 a sectional view of a third embodiment of a swirler 50 according to the invention is depicted. The swirler 50 comprises a plurality of vanes 54 extending from an outer radius 64 to an inner radius 62, only two of them marked with reference signs for lucidity. Between the vanes 54 a plurality of mixing channels 56 is located, of which only one is marked with a reference sign for lucidity. The mixing channels extend from an outer end 58 to an inner end 60. In this embodiment of a swirler 50 according to the invention, in each of the mixing channels 56 a main injection means 52 is positioned, each at a slightly different radial position. This contains the advantage that for different operation modes of the gas turbine engine 10 (not shown), for instance different load levels, a special set of main injection means 52, adjusted for instance in total number and/or pattern, can be used.

[0040] Further, at the inner end 60 of each of the mixing channels 56 and near a trailing edge 66 of the vanes 54, several pilot injection means 70 are located. At the inner end 60 of the mixing channels 56, especially due to the joining of the air flow of the different mixing channels 56 at the trailing edges 66 of the vanes 54, turbulences are additionally induced. These turbulences further enhance the atomization of the injected fuel out of the pilot injection means 70. Similar to the main injection means 52, the number and/or pattern of the pilot injection means 70 used for actual pilot fuel injection can be chosen according to the needs of the actual operation mode of the gas turbine engine 10. The pilot fuel is injected into the air such that the air transports the fuel into the intended region of a pilot flame of the burner 30 of the gas turbine engine 10 (not shown). A contact with any surface of the swirler 50 and/or the burner 30 can be avoided or at least significantly be reduced. Especially the danger of a carbon build up on surfaces in the swirler 50 and/or the burner 30 can therefore be reduced, if not completely avoided. An environmental friendly and fuel efficient operation of a gas turbine engine 10 comprising a burner 30 with a swirler 10 according to the invention can therefore be achieved.

[0041] FIG. 5 is a section through the swirler, burner, prechamber and part of the main combustion chamber as shown via section A-A in FIG. 4. The cut through vane has been removed for clarity. A central axis 31 extends through the combustor 16 about which the swirler 50 and burner 30 are generally arranged; the central axis is also shown in FIG. 1. The swirler 50 comprises a base plate 80 having a base plate surface 81 and an annular array of vanes 54 mounted on the base plate 80 at one of their axial ends. The base plate surface 81 faces the pre-chamber and main combustion chamber. At the other axial end the vanes 54 are capped by another plate 92 which can be part of the wall of the combustor can 27. The pre-chamber 93 is where the fuel/air mixture enters after egressing the mixing channel 52 and further mixing occurs before the fuel/air mixture is burnt in the main combustion chamber 28. A pilot flame 87 is shown schematically and radially inwardly of a main flame 86.

[0042] Referring at the same time to FIGS. 3 and 4, each vane 54 has a first side surface 82 and a second side surface 83 which meet at a trailing edge 66. The plurality of mixing channels 56 are partly formed by the first side surfaces 82, the second side surfaces 83 and the base plate surfaces 81. Additionally the plate 92 completes the form of the mixing channels 56 and its inlet and outlet. The vanes 54 have a height 85, in the axial direction, and in this case the height 85 is of the trailing edge 66 which is at an inner radius 64 from the central axis 31. As shown the trailing edge 66 is stepped back or is radially outwards of an inner edge 94 of the base plate 80. The radius of the inner edge 94 can vary significantly from the configuration shown. It is possible for the trailing edge 66 to be radially inward of the inner edge 94.

[0043] The swirler 50 further comprises at least one main injection means 52 for providing fuel for the main flame 86. As can be seen from the figures the main injection means 52 is arranged at and/or in at least one of the mixing channels 56. The pilot injection means 70 provides fuel for the pilot flame 87. The locations of the main and pilot injection into the air flow 24 are critical to ensure the main fuel/air mixture 95 is carried into the region of the main flame 86, while the fuel/air mixture 96 from the pilot injection is carried into the pilot flame 87 location. To ensure the main and pilot fuel/air mixtures 95, 96 are transported to the correct flame locations, the pilot injection means 70 has an outlet 88 that is arranged within 30% of the height 85 of the trailing edge from the base plate surface 81 and is between 80% and 150% of the inner radius 64. It should be appreciate that this swirler arrangement comprises a liquid fuel for the pilot injector and the pilot injection means is a liquid pilot injector or lance.

[0044] In FIG. 4 one particularly advantageous location of the pilot injection means 70 is in a turbulent mixing region, shown by shaded region 91, where fuel/air mixtures from adjacent mixing channels 54 meet at and move away from the trailing edge 66. The region 91 can be defined geometrically as a region between an extended plane 82 of the first side surface 82 and an extended plane 83 of the second side surface 83. To benefit from this particularly turbulent region of mixing fluids the pilot injection means 70 is located at least partly within the region 91. The pilot injection means 70 is located as close to the trailing edge 66 as possible so that fuel sprayed does not contact or has minimal contact with the surfaces 82, 83 of the vane 54. The location, force of the fuel spray, angle of the fuel spray and mass flow of the air flow 24 are all considered factors to determine how close the pilot liquid fuel injection means 70 can be to the trailing edge 66.

[0045] The pilot injection means 70 is at least partly housed within or through an orifice 89 which is defined in any one or more of the vane 54 or base plate 81 as seen in FIG. 3 for example. The pilot injection means 70, which can be a pilot injection lance 74, can protrude through the orifice as seen in FIGS. 3 and 5 or the fuel outlet or nozzle can be flush with the orifice 89/surfaces 81, 82, 83 or even recessed below the orifice 89/surfaces 81, 82, 83. This is also the case with the main fuel injection means 52 in relation to the orifice 90.

[0046] In general, in any one or all of the mixing channels 56 the pilot injection means 70 is arranged radially inwardly of the main fuel injection means 52. In one embodiment the pilot injection means 70 comprises pilot fuel injectors 70 arranged relative to alternate mixing channels 56 or vanes 54. That is to say that there is one pilot fuel injector per two mixing channels 56 or vanes 54. Similarly, the main injection means 52 comprise a main fuel injector 52 arranged relative to each alternate mixing channel 56 or vanes 54. Again there is one main fuel injector 52 per two mixing channels or vanes. In the case of the main fuel injectors 52 they are located in the mixing channels 56 although they could be each located radially outwardly of the mixing channels, but arranged to spray fuel into their respective mixing channel 56. The main and pilot fuel injectors 52, 70 are arranged in or relative to alternate mixing channels.